Paleontologists in the harsh, windswept terrain of the Argentine Andes have unearthed the fossilized remains of one of the oldest dinosaurs ever found. The discovery of a nearly complete and articulated skeleton in the La Rioja province of northwestern Argentina provides a rare glimpse into the early evolution of dinosaurs during the Late Triassic period, approximately 230 million years ago. The new species, a long-necked herbivore, challenges previous assumptions about the timeline of key evolutionary traits in the lineage that would eventually lead to the largest animals to ever walk the Earth.
The remarkably well-preserved fossil belongs to a previously unknown genus and species, which has been named Huayracursor jaguensis. Researchers estimate the creature lived between 225 and 230 million years ago, a critical time when dinosaurs were first appearing and diversifying alongside the ancestors of mammals. Analysis of the skeleton reveals a combination of features, particularly a longer neck and larger body size compared to its contemporaries, that suggest the signature characteristics of giant sauropods may have appeared much earlier in their evolutionary history than previously understood. The find, published in the journal Nature, not only introduces a new dinosaur but also opens a new window into a geological area that is just beginning to reveal the secrets of the dawn of the dinosaurs.
A Discovery High in the Andes
The skeleton of Huayracursor jaguensis was found in the Quebrada de Santo Domingo, a ravine situated at an elevation of about 3,000 meters (9,800 feet) above sea level. A team from Argentina’s National Council for Scientific and Technical Research (CONICET) was responsible for the find in this remote and inhospitable region, which until recently was virtually unexplored by paleontologists. The harsh environment, characterized by strong winds and low temperatures, contributed to the exceptional preservation of the fossil. The team, led by researchers from the Regional Centre for Scientific and Technological Transfer Research of La Rioja (CRILAR), successfully excavated a nearly complete vertebral column, a partial skull, and almost fully intact forelimbs and hindlimbs.
This discovery is significant not just for the age of the fossil, but for its location. For decades, Triassic fossils of this age in South America were primarily found in the Ischigualasto Formation in San Juan, southern La Rioja, and parts of southern Brazil. The unearthing of Huayracursor in this new geological basin provides scientists with a vital new location to study the diversification of early terrestrial fauna and reconstruct the ancient ecosystems of the Late Triassic. The name of the new dinosaur reflects its origins: “Huayra” is a Quechua word for wind, honoring the blustery conditions at the dig site, while “cursor” is Latin for runner. The species name, “jaguensis,” refers to the nearby village of Jagüé. Together, the name translates to the “Jagüé windrunner.”
Introducing Huayracursor jaguensis
Huayracursor jaguensis belongs to the sauropodomorphs, the group of herbivorous dinosaurs that includes the iconic long-necked giants like Argentinosaurus and Patagotitan. However, this early ancestor was considerably smaller. Scientists estimate that an adult Huayracursor measured approximately 2 meters (6.5 feet) in length and weighed around 18 kilograms (40 pounds). Despite its modest size, it was nearly double the size of some of its close relatives from the same period.
Early Emergence of Key Traits
The most scientifically striking features of Huayracursor are its physical proportions. According to the research team, the dinosaur exhibits two key characteristics that were previously thought to have evolved later in the sauropodomorph lineage: a significantly elongated neck and a larger body size relative to its contemporaries. This finding challenges the long-held theory of a gradual transition where these dinosaurs slowly evolved their massive necks and colossal sizes over millions of years. Huayracursor suggests that this evolutionary trend towards gigantism started very early and rapidly in the group’s history. The discovery provides a crucial data point, showing that the foundational traits for the evolutionary success of sauropods were in place at the very beginning of their diversification.
A Window into the Late Triassic
The fossil dates to the Late Triassic period, a pivotal era in Earth’s history that saw profound changes in global ecosystems. During this time, the supercontinent Pangea was beginning to break apart, and the climate was generally hot and arid. It was in this environment that the first dinosaurs emerged, competing with a variety of other reptiles and the earliest ancestors of modern mammals, known as cynodonts. The Quebrada de Santo Domingo site has also yielded fossils of other Triassic species, helping researchers build a more complete picture of this ancient world.
The discovery of Huayracursor helps paleontologists understand the fauna that inhabited this specific region of Pangea. As a primitive sauropodomorph, it was an herbivore, and its presence indicates a landscape capable of supporting a diverse community of plant-eating animals. The existence of a relatively large-bodied herbivore like Huayracursor so early in dinosaur history sheds light on the ecological dynamics of these nascent ecosystems and the evolutionary pressures that drove some dinosaur lineages toward gigantism.
Significance for Evolutionary Science
The unearthing of Huayracursor jaguensis is more than just the discovery of another ancient creature; it provides a crucial piece of the puzzle in dinosaur evolution. It demonstrates that the evolutionary path of sauropodomorphs was not a simple, linear progression from small, bipedal animals to lumbering giants. Instead, it suggests a more complex history of rapid, early innovation, where key traits like an elongated neck appeared much sooner than expected. This finding forces a re-evaluation of the evolutionary timeline and the mechanisms that drove sauropods to become the dominant terrestrial herbivores for over 100 million years.
Agustín Martinelli, a CONICET researcher and one of the study’s authors, emphasized the rarity and importance of the find, stating that it’s uncommon to discover entirely new sites with such an abundance of extraordinarily preserved fauna. The completeness of the Huayracursor skeleton allows for detailed anatomical studies that can clarify its relationship to other early dinosaurs, including those found in nearby Brazil. As research continues at this newly revealed fossil site, scientists are hopeful that more discoveries will further illuminate the dawn of the age of dinosaurs and the origins of the most colossal creatures to have ever lived on land.